Use of a syringe-mountable filter resin technique for the separation and enrichment of lead and cadmium prior to their determination by flame atomic absorption spectrometry

The use of a syringe-mountable filter resin (SMFR) technique for the separation and enrichment of lead and cadmium prior to their determination by flame atomic absorption spectrometry is described as a substitute for batch and column techniques. The proposed method was compared with the column technique with respect to ease of use, speed, reproducibility, simplicity, recovery and risk of contamination. The housing of a syringe-mountable membrane filter was filled with Dowex HCR cationic resin and mounted on to the tip of a plastic syringe. The sample solution was drawn into the syringe, passing through the resin and discharged manually. The elements sorbed by the resin were then quantitatively eluted by drawing and discharging 2.5 M HCl as the eluent. Under the optimum conditions, the recoveries of Pb and Cd were 98-99% with relative standard deviations (RSDs) of around 2%. Detection limits (3σ) were 14 μg l^-1 for Pb and 10 μg l^-1 for Cd. The elements could be concentrated by drawing and discharging several portions of sample successively but eluting only once. Pb and Cd added to a sea-water sample were quantitatively recovered (>95%) with low RSD values of around 2-3%. The proposed method is inexpensive, simple and precise. The risk of contamination is less than with the column technique. In addition, the method is much faster, easier and more practical than the column technique.